The lawsuit, filed by two Ethiopian researchers and the Kenya's Katiba Institute rights group, alleges that Facebook's recommendations systems amplified violent posts in Ethiopia, including several that preceded the murder of the father of one of the researchers.
Inciteful, hateful and dangerous posts "spark conversation, attract reactions and shares as well as motivate back-and-forth discussion in the comments section", read the petition seen by AFP.
It also accused Meta of "inhumane" working conditions for its overstretched content moderators in Nairobi tasked with overseeing eastern and southern Africa, a vast region covering 500 million people.
The petitioners claimed this resulted in "systematic discrimination" against African Facebook users, citing the platform's swift response by comparison to the attack on the US Capitol by supporters of former president Donald Trump on January 6, 2021.
The lawsuit also said Meta failed to exercise reasonable care in training its algorithms to identify dangerous posts and in hiring staff to police content for the languages covered by its regional moderation hub in Nairobi.
The plaintiffs are asking the court to order Meta to take emergency steps to demote violent content, increase moderation staff in Nairobi and create restitution funds of about $2 billion for global victims of violence incited on Facebook.
The father of Abrham Meareg, one of the Ethiopian researchers, faced ethnic slurs and calls for his death in Facebook posts in October 2021 that revealed where he lived, according to the lawsuit.
It alleges that Abrham reported them Facebook immediately but the company failed to remove them promptly or in some cases at all.
Abrham's father, an ethnic Tigrayan, was murdered on Nov. 3 2021, according to the lawsuit. Abrham told Reuters he held Meta "directly responsible" for his father's death.
"If Facebook had just stopped the spread of hate and moderated posts properly, my father would still be alive," said Abrham Meareg, who is ethnic Tigrayan and an academic like his father.
"I'm taking Facebook to court so no one ever suffers as my family has again. I'm seeking justice for millions of my fellow Africans hurt by Facebook's profiteering -- and an apology for my father's murder."
Meta spokesperson Erin McPike said hate speech and incitement to violence were against the rules of Facebook and Instagram.
"We invest heavily in teams and technology to help us find and remove this content," McPike said. "We employ staff with local knowledge and expertise and continue to develop our capabilities to catch violating content in the most widely spoken languages in" Ethiopia.
Meta's independent Oversight Board last year recommended a review of how Facebook and Instagram have been used to spread content that heightens the risk of violence in Ethiopia.
Thousands have died and millions have been displaced in the Ethiopian conflict that erupted in 2020 between the federal government and rebellious forces from the northern Tigray region. The two sides agreed in November to a permanent cessation of hostilities.
The case echoes accusations Meta has faced over content on its platforms related to violence elsewhere, including in Myanmar, Sri Lanka, Indonesia and Cambodia. The company has acknowledged being "too slow" to act in Myanmar.
This article was compiled with data from Reuters and Agence France-Presse.